Power supply circuits are known to produce a regulated output voltage or a plurality of regulated output voltages. A power supply may be implemented using one of a variety of different topologies. For example, a power supply may be implemented as a switch mode power supply utilizing a buck converter topology, a boost converter topology. a half bridge inverter topology, or a full bridge inverter topology. The particular topology used for a switch mode power supply typically depends on the output power requirements of the power supply. For instance, a power supply that produces lower power outputs will typically be implemented using a buck or boost converter while a power supply that produces higher power outputs will typically be implemented using a half bridge inverter or a full bridge inverter.
Such switch mode power supplies are regulated to produce a fixed output voltage(s), within specified tolerances, as the load varies. As such, regardless of the load, the output voltage(s) produced by a power supply remain constant.
A driver is known to receive a low power input signal and produce a high powered output signal. The driver may be used in audio applications to drive a headphone or speakers, it may be used in computer applications to drive data onto a bus, or in telecommunications applications to drive data onto telecommunication transmission mediums, such as fiber optics, twisted pair, Ethernet, et cetera. Such drivers are typically powered by an output of a power supply. As previously discussed, an output voltage of a power supply is a fixed regulated voltage.
As is known, power consumption of analog transistor circuitry, which is found within driver circuits, increases linearly with the source voltage. Thus, the higher the voltage. the more power is consumed by the circuitry. In most driver circuit applications. the input signals to the driver vary significantly over time such that the driver has a limited amount of time where it is required to operate at its maximum output voltage.
Thus, power consumption of a driver is often greater than it needs to be since the value of the fixed power supply is determined by maximum driver output voltage.
Therefore, a need exists for a method and apparatus that reduces power consumption in driver circuits by regulating the voltage powering the driver circuits.